The invention relates to drawing instruments or apparatus, and more specifically to drawing instruments intended primarily, but not exclusively for use as a toy by children in the creation of decorative patterns and designs of a varying nature. The invention is equally useful to artists, designers and similar professional persons.
There have been many proposals for drawing instruments or apparatus in the past. One well known drawing instrument involves the use of a toothed ring primary member and a toothed disc secondary member, both ring and disc each having a plurality of holes through which may be projected a pen, pencil or the like, so that the ring and disc may be moved relative to each other by the pen, pencil or the like, with the teeth of the primary and secondary members in mesh, and simultaneously produce a design on a surface supporting the drawing instrument. My U.S. Pat. No. Re. 26,341--Instruments or Apparatus discloses an instrument being marketed as Spirograph.RTM. Design Drawing Toy. The holes in the Spirograph.RTM. drawing instrument include round holes, of sufficient diameter only to accommodate the tip or writing point of a pen, pencil or the like, so that a design produced on the surface supporting the instrument when the pen, pencil or the like is engaged in a hole and is moved to cause relative movement between the two members, results only from such relative movement, the design produced not being dependent upon the shape of the hole. Thus restraints are inherent in the apparatus, and only designs in the epicyclic range are possible with the drawing instrument disclosed in this patent.
It has been discovered that the teeth of the primary member and the secondary member of the above described drawing instruments are prone to accidental disengagement, particularly by children, and difficulty is ofttimes experienced by children in maintaining the teeth of the primary and secondary members in mesh during operation of the instrument, so that very often a design is spoiled by the teeth of the primary and secondary members coming out of mesh.